Method for manufacturing optical display device and material roll for use therein

ABSTRACT

The invention provides a method for manufacturing an optical display device including an optical display unit and an optical film that includes a polarizing plate and is bonded to the optical display unit. The method comprises the steps of: unwinding and feeding a long sheet material from a roll of the long sheet material, wherein the long sheet material includes the optical film, a pressure-sensitive adhesive layer and a release film laminated in this order and has undergone a slitting process in a direction parallel or at a constant angle to an absorption axis of the polarizing plate so that it has a width corresponding to a short or long side of the optical display unit; inspecting the optical film of the fed long sheet material to detect a defect; cutting a part of the long sheet material other than the release film into a length corresponding to a long or short side of the optical display unit, while separating the detected defect; bonding a non-defective cut piece of the optical film to a surface of the optical display unit; and rejecting a defect-containing part of the optical film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for manufacturing an optical displaydevice including an optical display unit and an optical film thatincludes a polarizing plate and is bonded to the optical display unitand to a material roll for use in the method.

2. Description of the Related Art

A conventional method for manufacturing an optical display device suchas a liquid crystal panel includes previously forming an optical filmincluding a polarizer into a unit shape for a liquid crystal cell or thelike by stamping, and bonding the unit shape to the liquid crystal cellor the like. In addition, a pre-cut optical film used in this method cannot avoid an increase in the cost by a multi process and an increase inmanufacturing management cost by the storage and the management. This isbecause it requires, for example, end face processing to suppress theoverflow of the adhesive from the end face, packing in the clean roomatmosphere to avoid dust and dirt, the problem of the dirt and scratchcaused while transporting to the next process (for instance, bondingprocess for the panel), the inspection process accompanied with theproblem, and the management for the stock of each kind of the liquidcrystal cells. Moreover, bonding of the pre-cut optical film to theliquid crystal cell is done by the batch process. In the batch processof bonding, the pre-cut optical film is adjusted for its position one byone and then bonded to the liquid crystal cell. Therefore, the speed ofthe bonding cannot be raised, and a high-speed, continuous productionbecomes impossible. In addition, there are problems on dirt andcontamination with the adhesive at the end face, because the opticalfilms are stored in the form of stacking the end faces respectively.These problems cause the cost of the liquid crystal panel manufacturingto be increased as well as the cost of manufacturing the pre-cut opticalfilm.

Therefore, there are proposed various methods including winding a longoptical film such as a long polarizing plate into a roll, feeding andcutting the film from the roll, and continuously performing bonding ofthe cut piece. The continuous bonding method is useful, because theoptical film being fed can be inspected and examined on the line andthen bonded while defective portions are removed, so that the quality ofthe liquid crystal panel can be improved. The methods described beloware known to include the steps of inspecting a long optical film on theline and bonding the optical film in such a manner, while removingdefective portions of the optical film by cutting (see for exampleJapanese Patent Application Laid-Open Nos. 57-052017 and 2007-140046).

Japanese Patent Application Laid-Open No. 57-052017 discloses a methodfor manufacturing an optical display device, including unwinding andfeeding a long sheet material from a roll thereof, wherein the longsheet material includes an optical film, a pressure-sensitive adhesivelayer and a release film, inspecting the optical film for defects,sequentially cutting part of the long sheet material other than therelease film into pieces each with a length corresponding the size of anoptical display unit (when a defect is detected, the cutting isperformed again at a place immediately behind the position of thedefect), removing defect-containing short parts of the optical film, andthen bonding each of the remaining optical films to the surface of theoptical display unit.

However, such a defect inspection is performed using a mechanism inwhich a defective portion is removed by cutting when a sensor detectsit, and therefore, when a plurality of defects exist in regions close toone another, the process of cutting the optical film is interrupted dueto each response of the sensor to each defect. After all, defects inregions close to one another cause the problem of a reduction in bondingspeed. In particular, this method is unsuitable for production oflarge-screen televisions, the yield of which is required to be high.

Japanese Patent Application Laid-Open No. 2007-140046 discloses a methodincluding stamping or cutting an optical film into the desired size insuch a manner that defective portions can be separated based on theresult of defect inspection. In this method, however, a release filmthat protects a pressure-sensitive adhesive layer is also cut at thesame time, and therefore, the step of bonding the film to a liquidcrystal cell has to be performed in a batch mode. There has also beenthe issue of how to control the cutting width for removal of defectiveportions in the case that a plurality of defects exists in regions closeto one another.

In this regard, there is proposed a method of working an optical filmsuch as a polarizing plate, which includes determining whether each areaof the film is defective or not, based on the result of the inspectionof each area, and performing stamping or the like in such a manner thepositions of defects can be separated (Japanese Patent No. 3974400).This method may also be taken into account.

SUMMARY OF THE INVENTION

In the stamping method described above, however, the stamping edge hasto be controlled so as to move laterally in response to the position ofeach defect, when the defective portion is separated in the stampingprocess, and therefore, it is difficult to increase the cutting speed.In addition, as shown in FIG. 10, the process of stamping a long opticalfilm causes a lot of loss L and therefore inevitably increases the cost.In addition, since the portions to be used for products are obtained bystamping, the following bonding process has to be performed in a batchmode. Even taking into account the method disclosed in Japanese PatentNo. 3997740, therefore, it has been difficult to perform the bondingprocess in a high-speed, continuous-production mode, like the methodsdisclosed in Japanese Patent Application Laid-Open Nos. 57-052017 and2007-140046.

An object of the invention is to solve the problems with theconventional techniques described above and to provide an opticaldisplay device manufacturing method capable of reducing the total costand ensuring bonding accuracy and high-speed bonding. Another object ofthe invention is to provide a material roll suitable for use in such amanufacturing method.

The objects are achieved by the invention described below. Specifically,the invention is directed to a method for manufacturing an opticaldisplay device including an optical display unit and an optical filmthat includes a polarizing plate and is bonded to the optical displayunit, including the steps of: unwinding and feeding a long sheetmaterial from a roll of the long sheet material, wherein the long sheetmaterial includes the optical film, a pressure-sensitive adhesive layerand a release film laminated in this order and has undergone a slittingprocess in a direction parallel or at a constant angle to the absorptionaxis of the polarizing plate so that it has a width corresponding to theshort or long side of the optical display unit; inspecting the opticalfilm of the fed long sheet material to detect a defect; cutting a partof the long sheet material other than the release film into a lengthcorresponding to the long or short side of the optical display unit,while separating the detected defect; bonding a non-defective cut pieceof the optical film to the surface of the optical display unit; andrejecting a defect-containing part of the optical film.

The optical display device manufacturing method of the invention employsa roll of a long sheet material that includes an optical film, apressure-sensitive adhesive layer and a release film laminated in thisorder and has undergone a slitting process in a direction parallel or ata constant angle to the absorption axis of the polarizing plate so thatit has a width corresponding to the short or long side of the opticaldisplay unit. According to the method of the invention, therefore, theoptical film only has to be cut in the width direction. Moreover, aremaining portion in the width direction can be used, because the rollof the long sheet material is manufactured from a wide material roll byslitting it with the width corresponding to the width of the short sideor long side of the LCD product. Namely, it becomes possible to be ableto use the edge portions as a product of this invention, which aredisposed in the ordinal process, because the slit can be done again orat the same time according to size of LCD panel with the same width asthe edge portion or smaller, so that the area yield of the overall filmcam be improved greatly. Moreover, the release film can also be used asa carrier so that the process of bonding the optical film to a liquidcrystal cell or the like can be continuously performed, while theoptical film is transported, which allows a continuous production flowfrom inspection to bonding. Therefore, when continuous production isperformed according to the manufacturing method, there becomesadvantageous in contrast to conventional methods with regard to itstotal cost and manufacturing amount.

The invention is also directed to a method for manufacturing an opticaldisplay device including an optical display unit and an optical filmthat includes a polarizing plate and is bonded to the optical displayunit, including the steps of: unwinding and feeding a long sheetmaterial from a roll of the long sheet material, wherein the long sheetmaterial includes the optical film, a pressure-sensitive adhesive layerand a release film laminated in this order, has defect informationindentifying a defect position and has undergone a slitting process in adirection parallel or at a constant angle to the absorption axis of thepolarizing plate so that it has a width corresponding to the short orlong side of the optical display unit; cutting a part of the long sheetmaterial other than the release film into a length corresponding to thelong or short side of the optical display unit, while separating thedefect based on the defect information; bonding a non-defective cutpiece of the optical film to the surface of the optical display unit;and rejecting a defect-containing part of the optical film.

The optical display device manufacturing method of the invention alsoemploys the roll of the long sheet material having undergone a slittingprocess in a direction parallel or at a constant angle to the absorptionaxis of the polarizing plate so that it has a width corresponding to theshort or long side of the optical display unit. According to the methodof the invention, therefore, the optical film only has to be cut in thewidth direction, so that the loss L can be reduced. In addition, edgeportions, which would otherwise be discarded in conventional processes,can be used depending on the size of a liquid crystal cell or the like.In the method of the invention, the release film can also be used as acarrier so that the process of bonding the optical film to a liquidcrystal cell or the like can be continuously performed, while theoptical film is transported, which allows a continuous production flowfrom cutting to bonding. In this process, the roll used already hasdefect information identifying the defect positions so that the step ofdetecting defects can be omitted from a series of steps, which canfurther improve the manufacturing speed. Therefore, when continuousproduction is performed according to the manufacturing method of theinvention, a reduction in cost and an improvement in manufacturing speedcan be accelerated as more products are manufactured, in contrast toconventional methods.

The method of the invention preferably further includes the step ofproviding a roll of the long sheet material having undergone theslitting process so that it has a width corresponding to the short sideof the optical display unit and another roll of the long sheet materialhaving undergone the slitting process so that it has a widthcorresponding to the long side of the optical display unit, in which thelong sheet material having a width corresponding to the short sideshould be cut into a length corresponding to the long side, and the longsheet material having a width corresponding to the long side should becut into a length corresponding to the short side.

The above method employs a set of rolls including a roll havingundergone a slitting process so that it has a width corresponding to theshort side of the optical display unit and another roll having undergonea slitting process so that it has a width corresponding to the long sideof the optical display unit. According to this method, therefore,optical films of sizes corresponding to the short and long sides of theoptical display unit can be obtained, respectively, simply by cuttingthem into lengths corresponding to the long and short sides,respectively. At the same time, one of the optical films has anabsorption axis parallel or at a constant angle to the long side of theoptical display unit, and the other has an absorption axis parallel orat a constant angle to the short side. Therefore, the absorption axes ofthe optical films can be made orthogonal to each other with highaccuracy simply by bonding them to the upper and lower sides of theoptical display unit, respectively.

The optical display unit is preferably a VA or IPS mode liquid crystalpanel. Particularly when the optical display unit includes a VA or IPSmode liquid crystal panel, which has been used for large screen TVs orthe like in recent years, the polarizing plates of the first and secondoptical films should be so placed that their absorption axes can beorthogonal to each other and can be parallel to the directions of thelong and short sides of the optical display unit Therefore, the firstand second rolled materials each having undergone a slitting process ina direction parallel to the absorption axis only have to be unwound andcut in the width direction, so that a high production rate can beachieved. Particularly in the case of IPS mode, since the liquid crystaldirector is usually parallel or orthogonal to the side of LC panel innon-electric field, it is very important for obtaining a black displayto bond a polarizing plate so that the director is parallel to anabsorption axis of the polarizing plate. If this angle shifts, theinfluence of the retardation in the liquid crystal panel will arise, anoptical leakage is induced, and the fall of a contrast ratio is caused.Since in this invention the direction of the absorption axis of apolarizing plate is parallel to the long side or the short side of theoptical film and is bonded parallel to the short side or the long sideof a liquid crystal panel, the direction of the liquid crystal directorof LCD and the direction of the absorption axis can be coincided easily.

Also in the case of VA mode, since a contrast of black mode is high onlyin the direction of up and down or left and right, it is very importantfor obtaining a black display to bond a polarizing plate so that itsabsorption axis is parallel to the direction of the short side or thelong side of a liquid crystal panel.

The invention is also directed to a material roll for use in the processof cutting it into a specific-length piece to be bonded to an opticaldisplay unit, including: a roll of a long sheet material including theoptical film, a pressure-sensitive adhesive layer and a release filmlaminated in this order and having undergone a slitting process in adirection parallel or at a constant angle to the absorption axis of thepolarizing plate so that it has a width corresponding to the short orlong side of the optical display unit.

The material roll of the invention includes a roll of a long sheetmaterial including the optical film, a pressure-sensitive adhesive layerand a release film laminated in this order and having undergone aslitting process in a direction parallel or at a constant angle to theabsorption axis of the polarizing plate so that it has a widthcorresponding to the short or long side of the optical display unit.When the roll of the invention is used, therefore, the optical film onlyhas to be cut in the width direction. Moreover, a remaining portion inthe width direction can be used, because the roll of the long sheetmaterial is manufactured from a wide material roll by slitting it withthe width corresponding to the width of the short side or long side ofthe LCD product. Namely, it becomes possible to be able to use the edgeportions as a product of this invention, which are disposed in theordinal process, because the slit can be done again or at the same timeaccording to size of LCD panel with the same width as the edge portionor smaller, so that the area yield of the overall film cam be improvedgreatly. In addition, the release film can be used as a carrier so thatthe process of bonding the optical film to a liquid crystal cell can becontinuously performed, while the optical film is transported, whichallows a continuous production flow from inspection to bonding.Therefore, when continuous production is performed according to themanufacturing method, there becomes advantageous in contrast toconventional methods with regard to its total cost and manufacturingamount.

The optical display unit for use in bonding is preferably a VA or IPSmode liquid crystal panel for the same reason.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing a process for a production system for usein an embodiment of the invention;

FIG. 2 is a chart for illustrating an example of the production systemfor use in an embodiment of the invention;

FIG. 3 is a diagram for illustrating an example of the production systemfor use in an embodiment of the invention;

FIG. 4 is a diagram for illustrating the configuration of an example ofthe production system for use in an embodiment of the invention;

FIG. 5 is a diagram for illustrating the configuration of an example ofthe production system for use in an embodiment of the invention;

FIG. 6 is a diagram for illustrating the configuration of an example ofthe production system for use in an embodiment of the invention;

FIG. 7 is a diagram for illustrating the configuration of an example ofthe production system for use in an embodiment of the invention;

FIG. 8 is a diagram for illustrating an example of the laminatedstructure of first and second optical films; and

FIG. 9 is a schematic front view showing an example of the manufacturingapparatus for use in the material roll production method of theinvention.

FIG. 10 is a schematic diagram comparing an embodiment of the inventionwith a conventional method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some embodiments of the invention are described in detail below.

Material Rolls

As shown in FIG. 3, the material roll according to the invention, whichwill be cut into a specific length and then bonded to the surface of anoptical display unit, corresponds to a first roll R1 or a second rollR2. According to the invention, the material roll is preferably used ina process that includes cutting it into a piece with a specific length,while separating defects, and bonding the piece to the surface of anoptical display unit, more preferably used in the method of theinvention for manufacturing an optical display device.

The first roll R1 or the second roll R2 is a roll of a long sheetmaterial including a first optical film F11, a pressure-sensitiveadhesive layer and a release film laminated in this order, wherein thefirst optical film F11 includes a polarizing plate, and having undergonea slitting process in a direction parallel or at a constant angle to theabsorption axis of the polarizing plate so that it has a widthcorresponding to the short or long side of the optical display unit. Thelong sheet material is preferably wound on a core such as a core tube,while it may be wound alone.

As used herein, the phrase “corresponding to the long side of theoptical display unit” or “corresponding to the short side of the opticaldisplay unit” means that the length of the optical film to be bonded(exclusive of the length of the exposed portion) corresponds to thelength of the long or short side of the optical display unit and is notnecessarily the same as the length of the long or short side of theoptical display unit.

According to this embodiment, there is provided an example where thefirst and second rolls R1 and R2 have both undergone a slitting processin a direction parallel to the absorption axis of the polarizing plate,which forms each of them, so that they each have an absorption axis inthe longitudinal direction of the rolled material. Therefore, bonding isperformed with high accuracy so that an optical display device with goodoptical properties can be provided after the bonding process.Particularly when the optical display unit includes a VA or IPS modeliquid crystal panel, which has been used for large screen TVs or thelike in recent years, the polarizing plates of the first and secondoptical films should be so placed that their absorption axes can beorthogonal to each other, and therefore, the first and second rolledmaterials each having undergone a slitting process in a directionparallel to the absorption axis only have to be unwound and cut in thewidth direction, so that a high production rate can be achieved. Itwould be understood that when a TN mode liquid crystal cell is used, aroll having undergone a slitting process in a direction at an angle of45° to the absorption axis of the polarizing plate may be used. Forinstance, the slit direction to the absorption axis of the polarizingplate can be a direction of 45°, when using a material roll of thepolarizing plate stretched in diagonal direction and slitting itparallel to the longer direction of the material roll. In an embodimentof the invention, a roll having undergone a slitting process in adirection at a constant angle to the absorption axis of the polarizingplate may also be used.

For example, the influence of the axis accuracy during bonding on theoptical properties may be evaluated using the transmitted lightintensity and contrast ratio (CR) described below. Specifically, a firstroll of a polarizing plate (CAT1463DU manufactured by Nitto DenkoCorporation) having undergone a slitting process in a direction parallelto its absorption axis and a second roll of another polarizing platehaving undergone a slitting process at a certain angle with respect toits absorption axis were each cut into a square sample piece (50 mm×50mm) having a side parallel to the slitting direction. The two samplepieces were laminated, and the transmittance of the resulting laminatewas measured using a spectrophotometer U-4100 manufactured by HitachiHigh-Technologies Corporation. The result is shown in Table 1.

TABLE 1 Transmitted light Axis angle intensity CR Comparative 6059.04759 1.693549 Example 1 Comparative 67.5 77.96201 1.282676 Example 2Comparative 82.5 19.6158 5.097931 Example 3 Example 1 90 0.04136072417.754 Comparative 97.5 20.27872 4.931278 Example 4 Comparative 112.578.09852 1.280434 Example 5 Comparative 120 56.95775 1.755687 Example 6The result of Table 1 shows that, as compared Example 1 having the angleof 90° between the absorption axes with Comparative Examples having theangle between the absorption axes deviating from 90°, even when theangle between the absorption axes slightly deviates from 90°, lightleakage (the transmitted light intensity) becomes significant, and thecontrast ratio (CR) is significantly reduced.

Long Sheet Material

Any optical film including a polarizing plate may be used to form thelong sheet material. For example, such an optical film may be apolarizing plate or a laminate of a polarizing plate and one or more ofa retardation film and a brightness enhancement film. The polarizingplate may be of any type, as long as it includes a polarizer. Thepolarizing plate may include a polarizer and a polarizer protecting film(transparent protective film) provided on one or both sides thereof.

A protective transparent film may be placed on the surface of theoptical film. A pressure-sensitive adhesive layer is formed on onesurface of the optical film so that the optical film can be attached tosomething such as an optical display unit, and a release film isprovided to protect the pressure-sensitive adhesive layer. For example,a surface protecting film may also be provided on the other surface ofthe optical film with a pressure-sensitive adhesive layer interposedtherebetween.

Specifically, each optical film may have the structure shown in FIG. 8.For example, the laminated structure of the first sheet material F1includes a first optical film F11, a first release film F12, and asurface protecting film F13. The first optical film F11 includes a firstpolarizer F11 a, a first film F11 b provided on one side thereof with anadhesive layer (not shown) interposed therebetween, and a second filmF11 c provided on the other side thereof with another adhesive layer(not shown).

For example, the first and second films F11 b and F11 c are each apolarizer protecting film (such as a triacetylcellulose film or a PETfilm). The second film F11 c is bonded to the surface of an opticaldisplay unit with a first pressure-sensitive adhesive F14 interposedtherebetween. The first film F11 b may be surface-treated. Examples ofthe surface treatment include hard coating, anti-reflection treatment,anti-sticking treatment, diffusion treatment, antiglare treatment, andsurface treatment for any other purpose. The first release film F12 isprovided on the second film F11 c with the first pressure-sensitiveadhesive layer 14 interposed therebetween. The surface protecting filmF13 is provided on the first film F11 b with a pressure-sensitiveadhesive layer F15 interposed therebetween. Specific structures of thefirst and second films F11 b and F11 c are described later. Hereinafter,the laminated structure of the polarizer and the polarizer protectingfilm(s) is also referred to as polarizing plate.

The laminated structure of the second sheet material F2 may be the sameas, but not limited to, that of the first sheet material. The secondsheet material F2 includes a second optical film F21, a second releasefilm F22, and a surface protecting film F23. The second optical film F21includes a second polarizer F21 a, a third film F21 b provided on oneside thereof with an adhesive layer (not shown) interposed therebetween,and a fourth film F21 c provided on the other side thereof with anotheradhesive layer (not shown) interposed therebetween.

For example, the third and fourth films F21 b and F21 c are each apolarizer protecting film (such as a triacetylcellulose film or a PETfilm). The fourth film F21 c is bonded to the surface of the opticaldisplay unit with a second pressure-sensitive adhesive layer F24interposed therebetween. The third film F21 b may be surface-treated.Examples of the surface treatment include hard coating, anti-reflectiontreatment, anti-sticking treatment, diffusion treatment, antiglaretreatment, and surface treatment for any other purpose. The secondrelease film F22 is provided on the fourth film F21 c with the secondpressure-sensitive adhesive layer F24 interposed therebetween. Thesurface protecting film F23 is provided on the third film F21 b with apressure-sensitive adhesive layer F25 interposed therebetween.

Methods for Producing Material Rolls

The width of each of the first and second rolls R1 and R2 depends on thesize of the optical display unit to be bonded. Specifically, the widthof the first roll R1 is determined corresponding to the short side ofthe optical display unit, and the width of the second roll R2 isdetermined corresponding to the long side thereof. In this embodiment,therefore, the first and second rolls R1 and R2 have different widths,and material rolls (long materials) having undergone no slitting processare each previously subjected to a slitting process so as to have aspecific width, and the materials each with the specific width are used.

The method of slitting the material roll may be performed with orwithout rewinding, and any of the slitting method with rewinding andthat without rewinding may be used. In an embodiment of the invention,the slitting process may also be performed on the long sheet materialproduction line before the material is wound.

Therefore, the production method described below is preferably used asthe method of the invention for producing a material roll. Specifically,a method for producing a material roll for use in the process of cuttingit into a specific-length piece to be bonded to the surface of anoptical display unit includes: lengthwise slitting a long materialincluding an optical film, a pressure-sensitive adhesive layer and arelease film laminated in this order, wherein the optical film includesa polarizing plate, and having a longitudinal direction parallel to theabsorption axis of the polarizing plate, so that a long sheet materialhaving a width corresponding to the short or long side of the opticaldisplay unit is obtained; and winding the long sheet material into aroll.

FIG. 9 shows an exemplary material roll manufacturing apparatus that maybe used in the production method of the invention. The manufacturingapparatus includes an unwinding mechanism 40 to unwind a roll R0 of along material 55, a slitting mechanism 50 to slit the long material 55,and a winder 60 to wind the materials into rolls R1 and R2,respectively. When the slitting process is performed on the long sheetmaterial production line, the unwinding mechanism 40 is not necessary.

The unwinding mechanism 40 unwinds the long material 55 from the roll R0according to the tension by nip rollers 57. It includes nip rollers 57and a roll support to support and rotate the roll R0. The roll supportmay have a breaking mechanism, a driving mechanism, a tensioncontrolling mechanism, and so on.

The slitting mechanism 50 includes a slitting table 54 placed under thelong material 55 and a laser 51 placed above the long material 55. Thelaser irradiation position is fixed, and the long material 55 iscontinuously fed so that slitting proceeds. The laser 51 may be replacedby a slitter having a slitting blade or the like. In such a case, forexample, a rotatable circular slitting blade may be oriented in theslitting direction and placed at a predetermined interval, and the longmaterial 55 may be allowed to pass between the supported roll and theslitting blade so that slitting can be continuously performed.

The slitting mechanism 50 may be placed at each of positions along thewidth of the long material 55 (the drawing shows only a singleposition), and they may be shifted along the width direction of the longmaterial 55 so that the slitting width can be changed, and then fixed.For example, the slitting mechanism 50 may be placed at each of threepositions, and the two intervals between the irradiation positions maybe set to correspond to the short and long sides of the optical displayunit so that the material roll set of the invention, namely the rolls R1and R2, can be produced at the same time.

The winder 60 is an apparatus to wind the slit materials into rolls R1and R2, respectively. One or more winders 60 may be provided dependingon the number of the rolls to be formed after slitting. An additionalwinder to wind a scrap material in the same manner is preferablyprovided. In FIG. 9, the winder to wind a scrap material into a roll R3is equipped.

For example, the winder 60 includes winding units 61 and 62 to wind thematerials into the rolls R1 and R2, respectively, and each winding unithas a rotary drive mechanism capable of controlling tension. The windingunits 61 and 62 each have the function of fixing the core of each of therolls R1 and R2. In the winder 60, for example, the long sheet materials56 obtained after slitting may be wound at a constant speed by thewinding units 61 and 62, respectively, while the speed may be controlledby nip rollers 57 placed upstream of the winding units 61 and 62.

Optical Display Unit

Examples of the optical display unit for use in an embodiment of theinvention include a liquid crystal cell-glass substrate unit and anorganic electroluminescent (EL) light-emitting unit. In an embodiment ofthe invention, an optical display unit having a rectangular externalshape is effectively used. For example, an optical display unit with along side/short side ratio of 16/9 or 4/3 may be used. An optical filmor any other member may be previously integrated to form a laminate inthe optical display unit.

Production Flow Chart

FIG. 1 shows an example of the flow chart of a method for manufacturingan optical display device. FIG. 2 shows a schematic diagram of anexample of the optical display device production system. FIG. 3 shows aplan layout view of an example of the optical display device productionsystem.

The method of the invention for manufacturing an optical display deviceis a method for manufacturing an optical display device including anoptical display unit and an optical film that includes a polarizingplate and is bonded to the optical display unit. The manufacturingmethod of the invention includes a first cutting and bonding process anda second cutting and bonding process, wherein any one of these processesmay be performed first, or these processes may be performed at the sametime or substantially the same time.

The first cutting and bonding process includes cutting the material fromthe first roll to form a first optical film having a lengthcorresponding to the long side of the optical display unit and thenbonding the first optical film to one surface of the optical displayunit.

The second cutting and bonding process includes cutting the materialfrom the second roll to form a second optical film having a lengthcorresponding to the short side of the optical display unit and thenbonding the second optical film to the other surface of the opticaldisplay unit.

More specifically, the method of the invention for manufacturing anoptical display device includes the steps of: unwinding and feeding thelong sheet material from the roll described above; inspecting theoptical film of the fed long sheet material to detect a defect; cuttinga part of the long sheet material other than the release film into alength corresponding the long or short side of the optical display unit,while separating the detected defect; bonding a non-defective cut pieceof the optical film to the surface of the optical display unit; andrejecting a defect-containing part of the optical film. Each step willbe described below.

(1) Step of Providing First Material Roll (S1 in FIG. 1). The first rollof the first long sheet material described above is provided.

Each step described below is preferably performed in an isolatedequipment in a factory so that the cleanliness can be maintained. Inparticular, the cleanliness is preferably maintained in the step ofbonding the optical film to the optical display unit.

(2) Feeding Step (S2 in FIG. 1). The first sheet material F1 is unwoundand fed from the prepared and placed first roll to the downstream side.For example, a first feeder 12 to feed the first sheet material F1includes a pair of nip rollers, a tension roller, a rotary drive, anaccumulator A, a sensor, a controller, and so on.

(3) First Inspecting Step (S3 in FIG. 1). The first sheet material F1 isinspected for defects with a first defect inspection apparatus 14. Thedefect inspection method may be a method of performing imaging and imageprocessing on both sides of the first sheet material F1 with transmittedlight or reflected light, a method of performing imaging and imageprocessing with a polarizing film for inspection arranged in crossednicols relation (also referred to as “0° cross”) with the polarizationaxis of the polarizing plate (the object to be inspected) between a CCDcamera and the object, or a method of performing imaging and imageprocessing with a polarizing film for inspection arranged at a certainangle (for example, in the range of more than 0° to 10°, also referredto as “X° cross”) with the polarization axis of the polarizing plate(the object to be inspected) between a CCD camera and the object. Knownmethods may be used for the image processing algorithm. For example,defects may be detected by grayscale determination based onbinarization.

The method of performing imaging and image processing with transmittedlight allows the detection of contaminants in the first sheet materialF1. The method of performing imaging and image processing with reflectedlight allows the detection of contaminants deposited on the surface ofthe first sheet material F1. In the method of performing imaging andimage processing with 0° cross, surface contaminants, dirt, and interiorcontaminants can generally be detected as bright spots. In the method ofperforming imaging and image processing with X° cross, knicks cangenerally be detected.

Defect information detected by the first defect inspection apparatus 14is associated with the positional information (such as positioncoordinates) and sent to the controller 1 so that it can contribute tothe cutting process with a first cutting apparatus 16 as describedlater.

(4) First Cutting Step (S4 in FIG. 1). The first cutting apparatus 16cuts each of the surface protecting film F13, the pressure-sensitiveadhesive layer F15, the first optical film F11, and the firstpressure-sensitive adhesive layer F14 into a specific size withoutcutting the first release film F12. As a result, the first release filmF12 can be used as a carrying medium for the first optical film F11.

Concerning the length of the cut, the optical film is cut into a lengthcorresponding to the long side, because the first roll has a widthcorresponding to the short side. Concerning this embodiment, FIG. 3shows an exemplary case where the first material roll (the first sheetmaterial F1) has a width corresponding to the short side of the opticaldisplay unit W.

For example, the cutting means may be a laser, a cutter, or any otherknown cutting means. The cutting means may be configured so that defectscan be separated by cutting based on the defect information obtained bythe first defect inspection apparatus 14. This can significantly improvethe yield of the first sheet material F1. The system may be configuredso that the first sheet material F1 containing any defect can berejected by a first rejection apparatus 19 as described later so as notto be bonded to the optical display unit W.

(5) First Optical Film Bonding Step (S5 in FIG. 1). While the firstrelease film F12 is removed using a first peeling apparatus 17, thefirst optical film F11 separated from the first release film F12 isbonded to the optical display unit W with the first pressure-sensitiveadhesive layer F14 interposed therebetween using a first bondingapparatus 18. In the bonding step, the first optical film F11 and theoptical display unit W may be press-bonded between a pair of rolls (181,182) as described later.

(6-1) Cleaning Step (S6-1 in FIG. 1). For example, the surface of theoptical display unit W is cleaned using a polishing cleaning apparatusand a water cleaning apparatus. The cleaned optical display unit W istransported to an inspection apparatus by a transporting mechanism. Forexample, the transporting mechanism includes a transporting roller, atransporting direction-switching mechanism, a rotary drive, a sensor, acontroller, and so on. The polishing cleaning apparatus and the watercleaning apparatus will be described later.

(6-2) Inspection Step (S6-2 in FIG. 1). After the cleaning, the surfaceof the optical display unit W is typically inspected using an inspectionapparatus. After the inspection, the optical display unit W istransported to the first bonding apparatus 18 by a transportingmechanism.

The steps of providing the first material roll, first inspecting, firstcutting, bonding the first optical film, cleaning, and inspecting areeach preferably performed on a continuous production line. The firstoptical film F11 is bonded to one side of the optical display unit Wthrough a series of manufacturing steps as described above. Amanufacturing process for bonding the second optical film F21 to theother side is described below.

(7) Step of Providing Second Material Roll (S11 in FIG. 1). The secondroll of the second sheet material F2 described above is provided.

(8) Feeding Step (S12 in FIG. 1). The second sheet material F2 isunwound and fed from the prepared and placed second roll to thedownstream side. For example, a second feeder 22 to feed the secondsheet material includes a pair of nip rollers, a tension roller, arotary drive, an accumulator A, a sensor, a controller, and so on.

(9) Second Inspecting Step (S13 in FIG. 1). The second sheet material F2is inspected for defects with a second defect inspection apparatus 24.The defect inspection method may be the same as the above method usingthe first defect inspection apparatus.

(10) Second Cutting Step (S14 in FIG. 1). A second cutting apparatus 26cuts each of the surface protecting film F23, the pressure-sensitiveadhesive layer F25, the second optical film F21, and the secondpressure-sensitive adhesive layer F24 into a specific size withoutcutting the second release film F22. Specifically, since the second rollhas a width corresponding to the short side, the optical film is cutinto a length corresponding to the long side. Concerning thisembodiment, FIG. 3 shows an exemplary case where the second roll (thesecond sheet material F2) has a width corresponding to the long side ofthe optical display unit W.

For example, the cutting means may be a laser, a cutter, or any otherknown cutting means. The cutting means may be configured so that defectscan not be included in the domain to be bonded on the optical displayunit W by cutting based on the defect information obtained by the seconddefect inspection apparatus 24. This can significantly improve the yieldof the second sheet material F2. The system may be configured so thatthe second sheet material F2 containing any defect can be rejected by asecond rejection apparatus 29 as described later so as not to be bondedto the optical display unit W.

(11) Second Optical Film Bonding Step (S15 in FIG. 1). After the secondcutting step, while the second release film F22 is removed using asecond peeling apparatus 27, the second optical film F21 separated fromthe second release film F22 is bonded to the other side of the opticaldisplay unit W than the side bonded to the first optical film F11 withthe second pressure-sensitive adhesive layer F24 interposed therebetweenusing a second bonding apparatus 28. Before the second optical film F21is bonded to the optical display unit W, the optical display unit W maybe turned by 90° using a transporting direction-switching mechanism of atransporting mechanism R so that the second optical film F21 can bearranged in crossed nicols relation to the first optical film F11.

In an preferred embodiment of the invention, therefore, the methodfurther includes the step of turning the optical display unit W havingundergone the first cutting and bonding process to the direction ofbonding in the second cutting and bonding process or the step of turningthe optical display unit W having undergone the second cutting andbonding process to the direction of bonding in the first cutting andbonding process. In a preferred embodiment of the invention, the turningstep is performed so that the direction of the long side of the firstoptical film F11 bonded to the optical display unit W after the turningcan make an angle of 0±5°, preferably 0±1°, with the direction of thelong side of the second optical film F21 to be bonded after the cutting.For example, when the direction of the first optical film F11-feedingline is parallel to the direction of the second optical film F21-feedingline (including when they are on a straight line), the turning angle inthe turning step is preferably from 85° to 95°. In the bonding step, asdescribed later, the second optical film F21 and the optical displayunit W may be press-bonded between a pair of rolls.

(12) Step of Inspecting Optical Display Device (S16 in FIG. 1). Aninspection apparatus is used to inspect an optical display deviceincluding the optical display unit W and the optical films bonded toboth sides thereof. The defect inspection method may be a method ofperforming imaging and image processing on both sides of the opticaldisplay device with reflected light. Alternatively, the inspectionmethod may be a method using a polarizing film for inspection placedbetween a CCD camera and the object to be inspected. Known methods maybe used for the image processing algorithm. For example, defects may bedetected by grayscale determination based on binarization.

(13) Defect information obtained by the inspection apparatus is used todetermine whether the optical display device is non-defective. Theoptical display device determined as non-defective is transferred to thenext mounting process. When determined as defective, it is subjected toa reworking process, in which a new optical film is bonded, and then theproduct is inspected. The product determined as non-defective istransferred to the mounting process, but the product determined asdefective is subjected to the rewording process again or to disposal.

In a series of the manufacturing processes described above, the processof bonding the first optical film F11 and the process of bonding thesecond optical film F21 may be performed on a continuous production lineso that the optical display unit can be manufactured in a preferredmanner. In particular, each process may be performed in an isolatedequipment in a factory so that the optical film can be bonded to theoptical display unit in an environment with ensured cleanliness, whichallows the production of optical display devices of high quality.

In an embodiment of the invention, a set of rolls are used that includea roll having undergone a slitting process so that it has a widthcorresponding to the short side of the optical display unit and anotherroll having undergone a slitting process so that it has a widthcorresponding to the long side of the optical display unit. Therefore,optical films of sizes corresponding to the short and long sides of theoptical display unit can be obtained, respectively, simply by cuttingthem into lengths corresponding to the long and short sides,respectively. At the same time, one of the optical films has anabsorption axis parallel or at a constant angle to the long side of theoptical display unit, and the other has an absorption axis parallel orat a constant angle to the short side. Therefore, the absorption axes ofthe optical films can be made orthogonal to each other with highaccuracy simply by bonding them to the upper and lower sides of theoptical display unit, respectively.

Configuration of the Whole of Production System

Next, a description is given of the configuration of the whole of aproduction system for use in an embodiment of the invention. Theproduction system for use in an embodiment of the invention may be asystem for production of an optical display device including an opticaldisplay unit and an optically-anisotropic optical film bonded thereto,preferably a system for production of an optical display deviceincluding an optical display unit and an optical film that includes apolarizing plate and is bonded to the optical display unit. Theproduction system for use in an embodiment of the invention includes afirst cutting and boding apparatus for performing the first cutting andbonding process and a second cutting and bonding apparatus forperforming the second cutting and bonding process.

FIG. 3 shows an exemplary system of this embodiment including an opticaldisplay unit W feeding apparatus M1, a first optical film F11 feedingapparatus M2, a first bonding apparatus M3 for bonding the first opticalfilm F11, a feeder M4 for transporting and feeding the optical displayunit W after the bonding, a second optical film F21 feeding apparatusM5, and a second bonding apparatus M6 for bonding the second opticalfilm F21. In this example, the first cutting and bonding apparatusincludes the first optical film F11 feeding apparatus M2 and the firstbonding apparatus M3 for bonding the first optical film F11, and asecond cutting and bonding apparatus includes the second optical filmF21 feeding apparatus M5 and the second bonding apparatus M6 for bondingthe second optical film F21.

Concerning this embodiment, FIG. 3 shows an example where the firstoptical film F11 feeding apparatus M2, the first bonding apparatus M3,the feeder M4, the second optical film F21 feeding apparatus M5, and thesecond bonding apparatus M6 are linearly arranged, and the feedingapparatus M1 is placed so that the optical display unit W can be fed ina direction perpendicular to the panel flow direction in the firstbonding apparatus M3.

Configuration of Each Section in the Production System

An example of the configuration of each section in the production systemfor use in an embodiment of the invention is described below. FIG. 4shows a first feeder 12, a first pre-inspection peeling apparatus 13, afirst defect inspection apparatus 14, a first release film bondingapparatus 15, and a first cutting apparatus 16.

FIG. 5 shows a first peeling apparatus 17, a first bonding apparatus 18,and a first rejection apparatus 19. FIG. 6 shows a second feeder 22, asecond pre-inspection peeling apparatus 23, a second defect inspectionapparatus 24, a second release film bonding apparatus 25, and a secondcutting apparatus 26. FIG. 7 shows a second peeling apparatus 27, asecond bonding apparatus 28, and a second rejection apparatus 29.

The production system for use in an embodiment of the invention has theoptical display unit feeding apparatus M1 to feed the optical displayunit W. According to this embodiment, there is provided an example wherethe optical display unit feeding apparatus M1 includes a polishingcleaning apparatus, a water cleaning apparatus, and a dryer. In anembodiment of the invention, the optical display unit feeding apparatusM1 may include only a feeding mechanism R.

First, the polishing cleaning apparatus is described below. The opticaldisplay unit W is taken out of a storage box and placed on a feedingmechanism R. When the optical display unit W reaches a cleaningposition, the feeding is stopped, and the optical display unit W is heldat its end by holding means. A polishing means is brought into contactwith the upper surface of the optical display unit W from verticallyabove, and another polishing means is brought into contact with thelower surface of the optical display unit W from vertically below. Therespective polishing means are rotated on both surfaces of the opticaldisplay unit W, so that deposited contaminants are removed from bothsurfaces of the optical display unit W. Examples of the depositedcontaminants include minute glass particles (cullets) and fiberfragments.

Next, the water cleaning apparatus is described. The polished andcleaned optical display unit W is transported to a water bath by thefeeding mechanism R and then washed with water in the water bath. Purewater flows in the water bath. Both sides of the optical display unit Wtransported from the water bath are further rinsed and washed with purewater being discharged from a water flow pipe.

Water is then removed from the optical display unit W by blowing cleanair from the dryer. The optical display unit W is then transported tothe first bonding apparatus 18. In another embodiment, cleaning may beperformed using an aqueous ethanol solution in place of pure water. Instill another embodiment, the water bath may also be omitted.

The production system for use in an embodiment of the invention has afirst optical film feeding apparatus M2 that unwinds the long sheetmaterial F1 including the first optical film F11 from a roll thereof,cuts it into a specific length, and then feeds the cut piece. Accordingto this embodiment, there is provided an example where as shown in FIG.4, the first optical film feeding apparatus M2 includes a first feeder12, a first pre-inspection peeling apparatus 13, a first defectinspection apparatus 14, a first release film bonding apparatus 15, anda first cutting apparatus 16. In an embodiment of the invention, thefirst pre-inspection peeling apparatus 13, the first defect inspectionapparatus 14, and the first release film bonding apparatus 15 areprovided so that the first optical film can be inspected with highaccuracy. However, these apparatuses may be omitted.

In an embodiment of the invention, the first optical film feedingapparatus M2 is configured so that it can cut the optical film into alength corresponding to the long or short side of the optical displayunit, when the optical film has a width corresponding to the short orlong side of the optical display unit. According to this embodiment,there is provided an example where the first optical film feedingapparatus M2 is configured to cut the optical film with a widthcorresponding to the short side of the optical display unit into alength corresponding to the long side of the optical display unit.

The first roll of the first long sheet material F1 is mounted on a rollmount apparatus that is geared to a motor or the like to rotate freelyor at a certain speed. A controller 1 is provided to set the rotationalspeed and to control the drive.

The first feeder 12 is a feeding mechanism to feed the first sheetmaterial F1 to the downstream side. The first feeder 12 is controlled bythe controller 1.

The first pre-inspection peeling apparatus 13 is configured to peel offa release film H11 from the first sheet material F1 being fed and towind it around a roll 132. The speed of winding it around the roll 132is controlled by the controller 1. The peeling mechanism 131 has asharp-ended knife edge and is configured so that the release film H11can be peeled off by taking up the release film H11 with the knife edgeand turning the direction of the feeding and that the first sheetmaterial F1 peeled off from the release film H11 can be fed in thefeeding direction.

The first defect inspection apparatus 14 inspects defects after thepeeling of the release film H11. In the first defect inspectionapparatus 14, image data taken by the CCD camera are analyzed so thatdefects can be detected and that their position coordinates can becalculated and stored in the controller 1. In an embodiment of theinvention, the method preferably includes the step of storing theposition of the detected defect with respect to the coordinate in thelongitudinal direction of the long sheet material being transported asdescribed above. The defect position coordinate data may be used in theskip cutting process with the first cutting apparatus 16 as describedlater. The defect position coordinate data may also be used in theprocess of bonding the non-defective optical film with the first bondingapparatus 18. In an embodiment of the invention, defect positioncoordinates or the like may be attached to the material roll by a defectinspection previously performed as described above, and a skip cuttingprocess as described later (including the steps of bonding non-defectiveproducts after cutting and rejecting defective products) may beperformed based on such defect information in the process ofmanufacturing the optical display device using the material roll.

The first release film bonding apparatus 15 bonds a release film H12 tothe first optical film F11 with the first pressure-sensitive adhesivelayer F14 interposed therebetween after the first defect inspection. Asshown in FIG. 4, the release film H12 is unwound from a roll 151 of therelease film H12, and the release film H12 and the first optical filmF11 are inserted between one or more pairs of rollers 152 so that theyare bonded to each other under a certain pressure from the pair ofrollers 152. The rotational speed of the pair of rollers 152, thepressure, and the feeding are controlled by the controller 1.

The first cutting apparatus 16 cuts each of the first optical film F11,the surface protecting film 15, the first pressure-sensitive adhesivelayer F14, and the pressure-sensitive adhesive layer 15 into a specificsize without cutting the release film H12 after the bonding of therelease film H12. For example, the first cutting apparatus 16 is alaser. Based on the defect position coordinates detected by the firstdefect inspection, the first cutting apparatus 16 performs cutting insuch a manner that defective portions can be separated. Therefore, cutpieces having any defective portion are rejected as defective by thefirst rejection apparatus 19 in a later step. Alternatively, the firstcutting apparatus 16 may ignore defective portions and continuously cutthe material into a specific size. In this case, the bonding process maybe designed not to bond, but to remove the defective portions asdescribed later. In this case, the controller 1 may also function tocontrol the process.

According to the invention, the number of cutting operations can bereduced even when a plurality of defects exist in regions whose positioncoordinates are close to one another. For example, when the distancebetween the position coordinates of two defects close to each other isless than the desired length of a non-defective cut piece of the opticalfilm, a single piece having the defects may be formed by cutting so thatthe number of cutting operations can be reduced. Also when there aremore defects whose position coordinates are within a distance less thanthe desired length of a non-defective cut piece from one another, thenumber of defect-containing cut pieces can be reduced to be smaller thanthe number of the defects (for example, one piece).

In an embodiment of the invention, therefore, when the distance betweenthe position coordinates of two defects close to each other is less thanthe desired length of a non-defective cut piece of the optical film,cutting is preferably avoided at the location between the positioncoordinates of the defects in the process of cutting the optical filminto non-defective pieces with a specific length and separating thedetected defects. For example, the process of performing cutting in sucha manner includes previously storing, in the controller 1, the positionof each of the detected defects in correspondence with the coordinate inthe longitudinal direction of the fed long sheet material, determiningwhether the distance between the position coordinates of two defectsclose to each other is less than the desired length of a non-defectivecut piece of the optical film, and controlling the first cuttingapparatus 16 by the controller 1 in such a manner that the defect on theupstream side is not separated by cutting when the distance is less thanthe desired length. Also when there are more defects whose positioncoordinates are within a distance less than the desired length of anon-defective cut piece from one another, the number ofdefect-containing cut pieces can be reduced (for example, to one) bysequentially performing these steps.

For example, the first cutting apparatus 16 includes a holding tableplaced to adsorb and hold the first sheet material F1 from the back sideand a laser placed above the first sheet material F1. The laser is movedin the horizontal direction to scan the first sheet material F1 in thewidth direction, so that the first optical film F11, the firstpressure-sensitive adhesive layer F14, the surface protecting film F13,and the pressure-sensitive adhesive layer F15 are cut at a specificpitch in the feeding direction, while the release film H12 at the bottomis left uncut (hereinafter, the term “half cutting” will be used torefer to this process, as needed). The accumulator A of the feedingmechanism is configured to move upward and downward in the verticaldirection so that continuous feeding of the first sheet material F1 canbe prevented from being stopped on the upstream and downstream sideswhen the holding table adsorbs the first sheet material F1. Thisoperation is also controlled by the controller 1.

The production system for use in an embodiment of the invention has afirst bonding apparatus 18 (M3) that bonds the first optical film F11fed from the first optical film feeding apparatus M2 to one surface ofthe optical display unit W fed from the optical display unit feedingapparatus M1. According to this embodiment, there is provided an examplewhere as shown in FIG. 5, the first bonding apparatus 18 (M3) has apress roller 181 and a guide roller 182 and also includes a firstpeeling apparatus 17 and a first rejection apparatus 19. The firstrejection apparatus 19 has a rejection mechanism that works togetherwith the first cutting apparatus 16 to cut and reject defective portionsof the optical film. However, such a rejection mechanism may be omitted.

The first bonding apparatus 18 bonds the first sheet material F1 (firstoptical film F11) to the optical display unit W with the firstpressure-sensitive adhesive layer F14 interposed therebetween, after thefirst sheet material F1 undergoes the cutting process and is peeled offfrom the release film H12 by the first peeling apparatus 17. The firstsheet material F1 feeding route is placed above the optical display unitW feeding route.

In the bonding process, as shown in FIG. 5, the first optical film F11is bonded to the surface of the optical display unit W, while it ispressed against the surface by the press roller 181 and the guide roller182. The pressure from the press roller 181 and the guide roller 182 andthe driving operation thereof are controlled by the controller 1.

The peeling mechanism 171 of the first peeling apparatus 17 has asharp-ended knife edge and is configured so that the release film H12can be peeled off by taking up the release film H12 with the knife edgeand turning the direction of the feeding and that the first sheetmaterial F1 (first optical film F11) peeled off from the release filmH12 can be fed to the surface of the optical display unit W. The peeledrelease film H12 is wound around a roll 172. Winding it around the roll172 is controlled by the controller 1.

Specifically, in an embodiment of the invention, the first optical filmfeeding apparatus M2 has a feeding mechanism that feeds the firstoptical film F11 to the first bonding apparatus M3 by using, as acarrying medium, the release film provided on the optical film with thepressure-sensitive adhesive layer interposed therebetween.

The bonding mechanism includes a press roller 181 and a guide roller 182opposed thereto. The guide roller 182 includes a rubber roller whoserotation is driven by a motor, and is provided movable upward anddownward. The press roller 181 including a metallic roller whoserotation is driven by a motor is provided movable upward and downwardimmediately above the guide roller 182. When the optical display unit Wis fed to the bonding position, the press roller 181 is elevated to aposition higher than the upper surface so that the space between therollers is widened. Alternatively, the guide roller 182 and the pressroller 181 may each be a rubber roller or a metallic roller. Asdescribed above, the system is configured so that the optical displayunit W can be cleansed by any type of cleaning apparatus and fed by thefeeding mechanism R. The feeding mechanism R is also controlled by thecontroller 1.

A description is given of the first rejection apparatus 19 to reject thefirst sheet material F1 having any defect. When the first sheet materialF1 having a defect is transported to the bonding position, the guideroller 182 moves vertically downward. Subsequently, a roller 192 overwhich a remover film 191 is looped moves to the regular position of theguide roller 182. The press roller 181 is allowed to move verticallydownward to press the defect-containing first sheet material F1 againstthe pressure-sensitive adhesive tape 191. Therefore, thedefect-containing first sheet material F1 is bonded to the remover film191 and wound around a roller 193 together with the remover film 191.The remover film 191 can adhere the first sheet material F1 containing adefect using the adhesive power of the first adhesive layer F14 of thefirst sheet material F1, but it is also possible to use pressuresensitive adhesive tape as a remover film 191.

In an embodiment of the invention, when the non-defective optical filmis bonded as described above, the front end of the optical film ispreferably peeled off together with the pressure-sensitive adhesivelayer from the release film in advance using the peeling mechanism 171,and when the defective portion is rejected, the front end of the opticalfilm is also preferably peeled off together with the pressure-sensitiveadhesive layer from the release film in advance using the same peelingmechanism 171. According to this system, the rejection of the defectiveportion and the bonding of the non-defective material can be performedusing the same peeling mechanism so that the step of peeling off therelease film can be completed at a time and that the peeling apparatuscan be operated at a single place, which can simplify the configurationof the system and increase the bonding speed.

In the process of bonding the non-defective optical film using the firstbonding apparatus 18, whether the material is defective or not may bedetermined as described below by the controller 1. The position of eachof the detected defects are previously stored as described above in thecontroller 1 in correspondence with the coordinate in the longitudinaldirection of the fed long sheet material.

The coordinate of the optical film bonding position (such as the frontend of the peeling mechanism 171) in the longitudinal direction of thelong sheet material may be calculated as a relative coordinate from areference point (such as the defect detection position) according to thetransfer line length from the reference point to the bonding position.Even when the transfer line length is changed by the accumulator A orthe like, the transfer line length may be corrected for the change sothat the coordinate of the bonding position can be calculated. Forexample, the correction for the motion of the accumulator may becalculated as a function of the length of travel of its roller. Thecoordinate of the bonding position may also be calculated as an absolutecoordinate based on the coordinate in the longitudinal direction of thefed long sheet material.

As the position of the defect moves to the downstream side, the distancebetween the calculated coordinate and the coordinate corresponding tothe position of the defect decreases. For example, therefore, when thedistance between both coordinates is more than the desired length of anon-defective cut piece, the corresponding portion of the fed opticalfilm may determined to be non-defective, and when the distance betweenboth coordinates is less than the desired length of a non-defective cutpiece, the corresponding portion of the fed optical film may determinedto be defective. Therefore, whether the material is defective or not maybe determined based on the relationship between the calculatedcoordinate of the bonding position and the coordinate corresponding tothe position of the defect, and the controller 1 may control the systemso that the step of bonding a non-defective cut piece of the opticalfilm to the surface of the optical display unit and the step ofrejecting the defect-containing portion of the optical film can beselected and performed.

In this process, when the front end of the optical film is peeled off bythe peeling mechanism 171, the transfer line may be temporarily stoppedso that the coordinate of the bonding position can be determined basedon the position of the front end of the optical film at rest, whichallows more accurate determination of whether the material is defectiveor not. In a preferred embodiment of the invention, therefore, the frontend of the optical film peeled off by the peeling mechanism 171 shouldbe detected, and the transfer line should be temporarily stopped whenthe front end of the optical film is peeled off by the peeling mechanism171.

The optical display unit W having undergone the above process istransported to the downstream side, and the second optical film F21(second sheet material F2) is bonded thereto. Hereinafter, the same orsimilar components will be described only briefly.

The production system for use in an embodiment of the invention has afeeder M4 for transporting and feeding the optical display unit W afterthe bonding of the first optical film F11. The feeder M4 preferably hasa turning mechanism 20 that turns the optical display unit W to thedirection of bonding in the second bonding apparatus 28, after thebonding in the first bonding apparatus 18.

For example, when the second optical film F21 is bonded in 90° relation(crossed nicols relation) with the first optical film F11, the opticaldisplay unit W is turned by 90° by the feeding direction-switchingmechanism (turning mechanism 20) of the feeding mechanism R, and thenthe second optical film F21 is bonded thereto. The method describedbelow for bonding the second sheet material F2 includes performing eachstep, while keeping the second sheet material F2 turned upside down(with the release film facing upward), and bonding the second opticalfilm F21 to the lower side of the optical display unit W.

The production system for use in an embodiment of the invention has asecond optical film feeding apparatus M5 that unwinds the long sheetmaterial F2 including the second optical film F21 from a roll thereof,cuts it into a specific length, and then feeds the cut piece. Accordingto this embodiment, there is provided an example where as shown in FIG.6, the second optical film feeding apparatus M5 includes a second feeder22, a second pre-inspection peeling apparatus 23, a second defectinspection apparatus 24, a second release film bonding apparatus 25, anda second cutting apparatus 26. In an embodiment of the invention, thesecond pre-inspection peeling apparatus 23, the second defect inspectionapparatus 24, and the second release film bonding apparatus 25 areprovided so that the second optical film can be inspected with highaccuracy. However, these apparatuses may be omitted.

In an embodiment of the invention, the second optical film feedingapparatus M5 is configured so that it can cut the optical film into alength corresponding to the long or short side of the optical displayunit W, when the optical film has a width corresponding to the short orlong side of the optical display unit W. According to this embodiment,there is provided an example where the second optical film feedingapparatus M5 is configured to cut the optical film F21 with a widthcorresponding to the long side of the optical display unit W into alength corresponding to the short side of the optical display unit W.

As shown in FIG. 6, the second roll of the second long sheet material F2is mounted on a roll mount apparatus that is geared to a motor or thelike to rotate freely or at a certain speed. A controller 1 is providedto set the rotational speed and to control the drive.

The second feeder 22 is a feeding mechanism to feed the second sheetmaterial F2 to the downstream side. The second feeder 22 is controlledby the controller 1.

The second pre-inspection peeling apparatus 23 is configured to peel offa release film H21 from the second sheet material F2 being fed and towind it around a roll 232. The speed of winding it around the roll 232is controlled by the controller 1. The peeling mechanism 231 has asharp-ended knife edge and is configured so that the release film H21can be peeled off by taking up the release film H21 with the knife edgeand turning the direction of the feeding and that the second sheetmaterial F2 peeled off from the release film H21 can be fed in thefeeding direction.

The second defect inspection apparatus 24 inspects defects after thepeeling of the release film H21. In the second defect inspectionapparatus 24, image data taken by the CCD camera are analyzed so thatdefects can be detected and that their position coordinates can becalculated. The defect position coordinate data are used in the skipcutting process with the second cutting apparatus 26 as described later.

The production system for use in an embodiment of the invention has asecond bonding apparatus 28 (M6) that bonds the second optical film F21fed from the second optical film feeding apparatus M5 to the othersurface of the optical display unit W fed from the feeder M4. Accordingto this embodiment, there is provided an example where as shown in FIG.7, the second bonding apparatus 28 (M6) has a press roller 281 and aguide roller 282 and also includes a second peeling apparatus 27 and asecond rejection apparatus 29. The second rejection apparatus 29 has arejection mechanism that works together with the second cuttingapparatus 26 to cut and reject defective portions of the optical film.However, such a rejection mechanism may be omitted.

The second release film bonding apparatus 25 bonds a release film H22 tothe second optical film F21 with the second pressure-sensitive adhesivelayer F24 interposed therebetween after the second defect inspection. Asshown in FIG. 6, the release film H22 is unwound from a roll 251 of therelease film H22, and the release film H22 and the second optical filmF21 are inserted between one or more pairs of rollers 252 so that theyare bonded to each other under a certain pressure from the pair ofrollers 252. The rotational speed of the pair of rollers 252, thepressure, and the feeding are controlled by the controller 1.

The second cutting apparatus 26 cuts each of the second optical filmF21, the surface protecting film 25, the second pressure-sensitiveadhesive layer F24, and the pressure-sensitive adhesive layer 25 into aspecific size without cutting the release film H22 after the bonding ofthe release film H22. For example, the second cutting apparatus 26 is alaser. Based on the defect position coordinates detected by the seconddefect inspection, the second cutting apparatus 26 performs cutting insuch a manner that defective portions can be separated. Therefore, cutpieces having any defective portion are rejected as defective by thesecond rejection apparatus 29 in a later step. Alternatively, the secondcutting apparatus 26 may ignore defective portions and continuously cutthe material into a specific size. In this case, the bonding process maybe designed not to bond, but to remove the defective portions asdescribed later. In this case, the controller 1 may also function tocontrol the process.

The second cutting apparatus 26 includes a holding table placed toadsorb and hold the second sheet material F2 from the back side and alaser placed under the second sheet material F2. The laser is moved inthe horizontal direction to scan the second sheet material F2 in thewidth direction, so that the second optical film F21, the secondpressure-sensitive adhesive layer F24, the surface protecting film F23,and the pressure-sensitive adhesive layer F25 are cut at a specificpitch in the feeding direction, while the release film H22 at the bottomis left uncut. The accumulator A of the feeding mechanism is configuredto move upward and downward in the vertical direction so that continuousfeeding of the second sheet material F2 can be prevented from beingstopped on the upstream and downstream sides when the holding tableadsorbs the second sheet material F2. This operation is also controlledby the controller 1.

The second bonding apparatus 28 bonds the second sheet material F2(second optical film F21) to the optical display unit W with the secondpressure-sensitive adhesive layer F24 interposed therebetween, after thesecond sheet material F2 undergoes the cutting process and is peeled offfrom the release film H22 by the second peeling apparatus 27. In thebonding process, as shown in FIG. 7, the second optical film F21 isbonded to the surface of the optical display unit W, while it is pressedagainst the surface by the press roller 281 and the guide roller 282.The pressure from the press roller 281 and the guide roller 282 and thedriving operation thereof are controlled by the controller 1.

The peeling mechanism 271 of the second peeling apparatus 27 has asharp-ended knife edge and is configured so that the release film H22can be peeled off by taking up the release film H22 with the knife edgeand turning the direction of the feeding and that the second sheetmaterial F2 (second optical film) peeled off from the release film H22can be fed to the surface of the optical display unit W. The peeledrelease film H22 is wound around a roll 272. Winding it around the roll272 is controlled by the controller 1.

Specifically, in an embodiment of the invention, the second optical filmfeeding apparatus M5 has a feeding mechanism that feeds the secondoptical film F21 to the second bonding apparatus M6 by using, as acarrying medium, the release film provided on the optical film with thepressure-sensitive adhesive layer interposed therebetween.

The bonding mechanism includes a press roller 281 and a guide roller 282opposed thereto. The guide roller 282 includes a rubber roller whoserotation is driven by a motor, and is provided movable upward anddownward. The press roller 281 including a metallic roller whoserotation is driven by a motor is provided movable upward and downwardimmediately below the guide roller 282. When the optical display unit Wis fed to the bonding position, the press roller 281 is shifted to alower position so that the space between the rollers is widened.Alternatively, the guide roller 282 and the press roller 281 may each bea rubber roller or a metallic roller.

A description is given of the second rejection apparatus 29 to rejectthe second sheet material F2 having any defect. When the second sheetmaterial F2 having a defect is fed to the bonding position, the guideroller 282 moves vertically upward. Subsequently, a roller 292 overwhich a remover film 291 is looped moves to the regular position of theguide roller 282. The press roller 281 is allowed to move verticallyupward to press the defect-containing second sheet material F2 againstthe remover film 291. Therefore, the defect-containing second sheetmaterial F2 is bonded to the remover film 291 and wound around a roller293 together with the remover film 291.

The optical display device having the bonded first and second sheetmaterials is transported to an inspection apparatus. The inspectionapparatus inspects both sides of the optical display device transportedthereto. The light source and a half mirror are used to verticallyilluminate the upper surface of the optical display device, and thereflected light is captured as image data by a CCD camera. The oppositesurface is also inspected using a light source and a CCD camera. Thelight source also illuminates the surface of the optical display deviceat a certain angle, and the reflected light is captured as image data bythe CCD camera. The opposite surface is also inspected using the lightsource and the CCD camera. These image data are subjected to imageanalysis to determine whether the product is defective or not.

For example, the timing of the operation of each apparatus is calculatedby a method using sensors placed at specific locations or by a method ofdetecting the rotating part of the feeder or the feeding mechanism Rwith a rotary encoder or the like. The controller 1 may be implementedin cooperation with software programs and hardware resources such as CPUand memories. In this case, program software, procedures, varioussettings, and so on are previously stored in memories. Private circuits,firmware, or the like may also be used for the implementation.

The optical film according to the invention is preferably used to forman image display device (corresponding to the optical display device)such as a liquid crystal display device, an organic electroluminescence(EL) display device or a plasma display panel (PDP).

The optical film according to the invention is preferably used to formany of various devices such as liquid crystal display devices. Liquidcrystal display devices may be formed according to conventionaltechniques. Specifically, a liquid crystal display device may betypically formed by assembling a liquid crystal cell (corresponding tothe optical display unit) and optical films, and optional componentssuch as a lighting system and incorporating a driving circuit, accordingto any conventional techniques, except that the optical films are usedaccording to the invention. The liquid crystal cell to be used may alsobe of any type such as TN type, STN type or π type.

Any appropriate liquid crystal display device may be formed such as aliquid crystal display device including a liquid crystal cell and theoptical film placed on one or both sides of the liquid crystal cell or aliquid crystal display device using a backlight or a reflector in alighting system. In that case, the optical film according to theinvention may be placed on one or both sides of the liquid crystal cell.The optical films placed on both sides may be the same or different. Inthe process of forming the liquid crystal display device, one or morelayers of an additional appropriate component or components such as adiffusion plate, an antiglare layer, an anti-reflection film, aprotective plate, a prism array, a lens array sheet, a light diffusionplate, and a backlight may also be placed at an appropriate location orlocations.

The optical film according to the invention is preferably used to formvarious devices such as liquid crystal display devices. The optical filmaccording to the invention may be placed on one or both sides of aliquid crystal cell to form a liquid crystal display device having anappropriate structure according to conventional techniques, such as atransmissive, reflective or transflective liquid crystal display device.The liquid crystal cell used to form a liquid crystal display device maybe of any type. Any appropriate type of liquid crystal cell such as asimple matrix driving type typified by a thin film transistor type maybe used.

The polarizing plates or the optical components provided on both sidesof a liquid crystal cell may be the same or different. In the process offorming a liquid crystal display device, one or more layers of anadditional appropriate component or components such as a prism arraysheet, a lens array sheet, a light diffusion plate, and a backlight maybe placed at an appropriate location or locations.

Other Embodiments of the Production System

The respective apparatuses of the production system for use in anembodiment of the invention may be arranged in any other way. Forexample, the optical display unit W feeding apparatus M1, the firstoptical film F11 feeding apparatus M2, and the first bonding apparatusM3 may be linearly arranged. At the same time, the second optical filmF21 feeding apparatus M5 and the second bonding apparatus M6 may bearranged parallel thereto, and the feeder M4 may be placed between thefirst bonding apparatus M3 and the second bonding apparatus M6.

In an embodiment of the invention, the mechanism to turn the opticaldisplay unit W may be omitted. In such a case, the first optical filmF11 feeding apparatus M2 and the first bonding apparatus M3 arepreferably arranged perpendicular to the second optical film F21 feedingapparatus M5 and the second bonding apparatus M6.

What is claimed is:
 1. A method for manufacturing an optical displaydevice including an optical display unit and an optical film thatincludes a polarizing plate and is bonded to the optical display unit,comprising the steps of: unwinding and feeding a long sheet materialfrom a roll of the long sheet material, wherein the long sheet materialincludes the optical film, a pressure-sensitive adhesive layer and arelease film laminated in this order and has undergone a slittingprocess in a direction parallel to an absorption axis of the polarizingplate so that it has a width corresponding to a long side of the opticaldisplay unit; inspecting the optical film of the fed long sheet materialto detect a defect; cutting a part of the long sheet material other thanthe release film into a length corresponding to a short side of theoptical display unit, while separating the detected defect; bonding anon-defective cut piece of the optical film to a surface of the opticaldisplay unit; and rejecting a defect-containing part of the opticalfilm, wherein the inspecting the optical film to detect a defectcomprises: storing a position of the detected defect, determining anoptical film bonding position, determining whether a distance betweenthe position of the detected defect and the optical film bondingposition is less than the length corresponding to the short side of theoptical display unit, and judging that a corresponding portion of thefed optical film is defective when the distance between the position ofthe detected defect and the optical film bonding position is less thanthe length corresponding to the short side of the optical display unit.2. A method for manufacturing an optical display device including anoptical display unit and an optical film that includes a polarizingplate and is bonded to the optical display unit, comprising the stepsof: unwinding and feeding a long sheet material from a roll of the longsheet material, wherein the long sheet material includes the opticalfilm, a pressure-sensitive adhesive layer and a release film laminatedin this order, has defect information indentifying a defect position andhas undergone a slitting process in a direction parallel to anabsorption axis of the polarizing plate so that it has a widthcorresponding to a long side of the optical display unit; and cutting apart of the long sheet material other than the release film into alength corresponding to a short side of the optical display unit, whileseparating the defect based on the defect information; bonding anon-defective cut piece of the optical film to a surface of the opticaldisplay unit; and rejecting a defect-containing part of the opticalfilm, wherein the separating the detected defect based on the defectinformation comprises: storing a position of the detected defect,determining an optical film bonding position, determining whether adistance between the position of the detected defect and the opticalfilm bonding position is less than the length corresponding to the shortside of the optical display unit, and judging that a correspondingportion of the fed optical film is defective when the distance betweenthe position of the detected defect and the optical film bondingposition is less than the length corresponding to the short side of theoptical display unit.
 3. The method according to claim 1 or 2,comprising the step of providing a roll of the long sheet materialhaving undergone the slitting process so that it has a widthcorresponding to the short side of the optical display unit and anotherroll of the long sheet material having undergone the slitting process sothat it has a width corresponding to the long side of the opticaldisplay unit, wherein the long sheet material having a widthcorresponding to the short side is cut into a length corresponding tothe long side, and the long sheet material having a width correspondingto the long side is cut into a length corresponding to the short side.4. The method according to any one of claim 1 or 2, wherein the opticaldisplay unit is a VA or IPS mode liquid crystal panel.